(1) Field of the Invention
This invention relates to agricultural irrigation and more particularly to an irrigation system having a pipe which moves laterally.
(2) Description of the Prior Art
Furrow guides for tractors used for agricultural purposes are old and well known. These furrow guides include a pair of discs which are attached to a leg which are attach to the front wheels or steering mechanism of the tractor. Therefore, if they are placed in the furrow, they will cause the tractor to be faithfully guided along the furrow. With the tractor following the furrows, there would be no need for the operator to constantly maintain and steer the tractor manually.
My prior U.S. Pat. No. 3,417,766, discloses a means for automatically maintaining the intermediate vehicles of an irrigation system in alignment between the end vehicles. The system is driven by a shaft extending along the side of the elongated pipe and any mis-alignment would result in the change of the length of the shaft. This change in the length of the shaft is used to vary the effective diameter of variable diameter sheaves so that a mis-aligned vehicle is either speeded up or slowed down.
My prior U.S. Pat. No. 3,844,308, discloses a dirigible irrigation system. In it, by manually changing a cable, the effective diameter of variable diameter sheaves on the end vehicles was changed. The other vehicles being aligned between the end vehicles and, therefore, the angle of travel of the entire system could be changed by this manual correction.
McMurray, U.S. Pat. No. 3,726,478, discloses a system whereby the speed of the end vehicles was controlled by a trolley which followed a concrete curb along the edge of a permanent canal in the field. The distance between the curb and the end of the vehicle was determined and the speed of the end vehicle was changed so as to change the angle of the pipe, thus, maintaining the end of the pipe a fixed distance from the curb.
Christensen et al., U.S. Pat. No. 3,979,062, discloses an irrigation system which moves in a circle around a center pivot. In order to irrigate corners of a field, a wire is buried adjacent to the perimeter of the circle and by different positions of the wire, signals are given to control a function of the irrigation system, namely, to water the corner.
My prior U.S. Pat. No. 3,444,941, discloses an automatic irrigator wherein a special vehicle straddling the permanent supply pipe to connect to each valve on the supply pipe to furnish water to the moving pipe.
In the prosecution of the parent application, the Examiner made of record Lundegreen U.S. Pat. No. 2,744,785, Nelson U.S. Pat. No. 3,235,009 and Baldocchi U.S. Pat. No. 3,785,564; however, applicant does not consider them as pertinent as the specific prior art as discussed above.